The ion conductive characteristics of solid electrolyte materials have found widespread applications in industrial and process control environments for monitoring and controlling gas constituents. The operation of the conventional solid electrolyte electrochemical cell as a gas measuring device is generally operated in accordance with the Nernst equation wherein an EMF is generated in response to a change in the partial pressure of the gas constituent at elevated temperatures. A detailed description of the construction and operation of such an electrochemical cell for oxygen measurements is described in Reissue U.S. Pat. No. 28,792 which is assigned to the assignee of the present invention and incorporated herein by reference. Inasmuch as elevated temperatures are required to achieve optimum ion conduction, and temperature is a variable in the Nernst equation, it is generally recognized that in order to equate the gas measurement directly to the generated EMF, it is essential to maintain the temperature of the cell at a constant level.
There is described herein with reference to the accompanying drawings a preferred technique for controlling a heater element such as that associated with a solid electrolyte electrochemical cell employed for gas measurements.